Cannot find module "SwiftyStoreKit" in Pods

## Bug Report
Pulling the `develop` branch from Pods produces an error "Cannot find module "SwiftyStoreKit", and is missing the source files.

This seems to happen after some changes made to support Xcode 12?

**To Reproduce**
1. Specify develop branch in Podfile

```pod 'SwiftyStoreKit', :git => 'https://github.com/bizz84/SwiftyStoreKit.git', :branch => 'develop'```

2. Run `pod install`

3. Build and observe error.

**Expected behavior**
Should be able to install.

For now, a workaround is to specify an earlier commit.

``` pod 'SwiftyStoreKit', :git => 'https://github.com/bizz84/SwiftyStoreKit.git', :commit => 'd0b80c0021f0107d172e18f271458160d124a3fb'```

## Platform Information
- Running Xcode 11